What are the layoffs of PetroChina?

There are four ways to reduce employees: natural retirement and reduction; Control new employees; Dismissal after the expiration of the contract; Merge some positions. The first two don't have much objection, the key is the latter two. It seems that employees whose contracts have expired should be laid off first. I'm afraid these employees are so-called "temporary workers". Originally, the position was unstable, and now it is "no accident". Naturally, it is the first one to be cleared out of the PetroChina team.